Understanding the Number System

At The Stone, we employ something called the Number System with our musicians. One of the most frequent questions we get asked is, “I downloaded one of your chord charts but it just had numbers on it! Why not just put chords?”

While chord names are certainly a quicker way to just jump into playing the song, the Number System is a far more flexible system for the long-term use of the song.

Enter the Number System. It allows you to quickly transpose songs on the fly.

The Basics

It’s based on one simple principle: the notes in a key’s major scale are numbered one through seven, each of which represents a chord.

That’s it. So, let’s take the key of C as a simple example.

The C Major scale is:
C – D – E – F – G – A – B

So we would number them as such:
1=C, 2=D, 3=E, 4=F, 5=G, 6=A, 7=B

You’re already probably beginning to see how easy this can be! So, if you see a chord sheet that says:

1 – 5 – 4

… you will know that those notes, in the Key of C Major would be: C – G – F.

Therefore, if you know your major scales for each key, you can easily know the notes for any key using the same chart. No need to write out a new chart for a different key.

So if the worship leader says, “we’re going to do the song in B instead of C”, you can still look at the same chart:

1 – 5 – 4

… and know that those notes in a B Major scale would be: B – F# – E

Side Note: This is the exact same concept as “do re mi fa so la ti do” — a vocalist would know that no matter what key they are in, “mi” is 3rd note of the scale, “la” is the 6th, and so on.

Building Chords

The second part of the number system is knowing which numbers in the scale are inherently major chords and which are inherently minor chords.

For example, if we added a “6” to our progression above (1 – 5 – 6 – 4), you might be tempted to play C – G – A – F. Those would indeed be the correct notes, but the 6 is inherently a minor chord, so it would actually be: C – G – Am – F.

“Why? And how do I know?” Glad you asked!

Basic chords are built on triads. A triad is just what it sounds like: three notes. To build a triad, take every other note from the scale you are using (in this simple example, the Major scale). The resulting notes make up the chord.

So, a C Major Chord starts on the “1” and takes every other note. You end up with the 1, 3, and 5 notes: C, E, and G. This is the “1” chord.

When you see a “4” chord on the chart, you know that it will be an F chord, and the notes will be F, A, and C (wrapping around to the beginning of the scale again). This is because when you start at the 4th note and build a triad using every other note, you’ll be using: 4 – 6 – 1, which is F – A – C.

But, with our example of the “6” chord, what notes make up that chord? 6 – 1 – 3 would make up that chord (A – C – E), and that is an A minor, not A major (which would be A – C# – E).

If a chord chart reads 1 – 5 – 6 – 4, you could now quickly transpose from C to G if you needed to, using the same chart.
In the Key of C: C – G – Am – F
In the Key of G: G – D – Em – C

Notations

It is necessary to mention a couple of ways that you may see chords notated using the Number System.

In your average chart, numbers by themselves simply represent what I laid out above: the default chords based on that number. The 1, 4, and 5 chords will by default be major chords, the 2, 3, and 6 chords will be default be minor chords, and the 7 chord will by default be a diminished chord.

However, there are a few alterations you may see that are worth noting:
Sometimes a minor chord will be denoted with a lower case “m”; for example, “6m”. This is no different than the default notation of simply “6”, but it is sometimes used to help aid in remembering it’s a minor chord.
If a chord has a capital “M” by it (such as “6M”), this means that it is a major chord of that note degree. So whereas the 6 chord ordinarily be minor, the chart is telling you this time it’s a major chord.

You will often see a chord notated as something like “5/7” or “1/3”. This refers to an inversion of a chord, where the first number is the chord itself, and the second number is the bass note of the chord. For example, in the Key of C, “5/7” would mean “G/B” — this means I’ll play a G chord with a B as the bass note. A “1/3” chord would mean a C chord with an E as the bass note. Bass players need to be especially mindful of this!

Additional notations will extend the chord beyond a triad: 4M7 would be the 4 chord as a Major 7th; 2m7 would be the 2 chord as a Minor 7th; 5sus4 would be the 5 chord as a Suspended 4th (ie. add the 4 note into a 5 chord).

Another way to use the Number System is with Roman Numerals. While it is not as common, it does have a specific advantage: upper case Roman Numerals indicate Major chords, while lower case Roman Numerals indicate Minor chords. Using our example above, 1 – 5 – 6 – 4 would be notated as I – V – vi – IV. It helps you to notice at a quick glance that the 6 chord is a minor.

So that’s it! I hope that’s a helpful introduction to the Number System. Transpose away.

About Kyle Lent

Kyle Lent serves as the Creative Director of Albums for Austin Stone Worship, leads worship with Aaron Ivey, and loves producing records for other artists in his spare time. He lives in Austin with his wife Annie and his two daughters, Norah and Josie.